The present invention relates to an apparatus and a method for controlling a variable valve mechanism, in an internal combustion engine provided with an intake side variable valve mechanism varying an open-close characteristic of an intake valve and an exhaust side variable valve mechanism varying an open-close characteristic of an exhaust valve.
Heretofore, there has been known an apparatus in which a target torque is calculated based on an accelerator opening and an engine rotation speed, and an open-close characteristic of an intake valve is varied so that a target intake air amount corresponding to the target torque can be obtained (refer to Japanese Unexamined Patent Publication No. 6-272580).
Further, there has also been known a variable valve event and lift mechanism varying continuously valve lift amounts and operating angles of engine valves (intake valve and exhaust valve) (refer to Japanese Unexamined Patent Publication No. 2001-012262)
In the case where an open-close characteristic of an intake valve (valve lift amount and/or valve timing) is variably controlled so as to obtain a target intake air amount, it becomes necessary to change the open-close characteristic of the intake valve over a wide range.
Consequently, there is a possibility that interference between the intake valve and exhaust valve occurs or the combustibility is degraded due to a change in valve overlap amount.
The present invention has been accomplished in view of the above problems and has an object to avoid interference between valves or combustibility degradation, while controlling an open-close characteristic of an intake valve to a requested characteristic according to operating conditions.
In order to achieve the above object, according to the present invention, the constitution is such that an open-close characteristic of an intake valve is determined based on operating conditions of an internal combustion engine to control an intake side variable valve mechanism, and also an open-close characteristic of an exhaust valve is determined according to the open-close characteristic of the intake valve to control an exhaust side variable valve mechanism.